1. Field
The following description relates to a digital video recorder (DVR), and more particularly, to a network DVR or a hybrid DVR.
2. Description of the Related Art
Digital video recorders (DVRs) are devices to compress and store or display video is signals captured by a plurality of video cameras connected thereto in a wired manner, and have been widely used for security purposes for buildings, offices, automated teller machines (ATMs), and the like.
Conventionally, video signals captured by a video camera such as an analog CCTV camera are converted into analog signals by a video encoder, and the analog signals are transmitted to a DVR. The analog signals are converted into digital signals through analog-to-digital conversion (ADC) performed by a video decoder, and the digital signals are compressed and then played or transmitted. However, in reality, it is not easy to provide equipment for effectively transmitting video signals captured by thousands of video cameras to a control center via thousands of cable lines.
With recent developments in network and camera technologies, IP cameras that compress digital images and transmit the compressed digital images to a network and network DVRs that store compressed video streaming data provided by IP cameras have been widespread.
Devices that record and play image data provided by IP cameras are referred to as network DVRs, and devices that record, play and transmit not only image data provided by typical analog cameras but also image data provided by IP cameras are referred to as hybrid DVRs.
FIG. 1 illustrates an example of a system including a conventional DVR.
Referring to FIG. 1, a DVR 110, a plurality of IP cameras 120, a network storage 130 such as a network-attached storage (NAS), and a personal computer (PC) for external monitoring are connected to a communication network via a network switch 150.
The DVR 110 may be a network DVR or a hybrid DVR. However, in response to too many packets are being generated by the PC 140 due to a computer virus, the packets may all be broadcast to all the devices connected to the communication network, thereby causing various problems. For example, the packets may be transmitted to the DVR 110, the IP cameras 120, and the network storage 130 that are all connected to the network switch 150, and may cause a considerable amount of interrupts to be generated in the CPUs of the DVR 110, the IP cameras 120, and the network storage 130. As a result, the data processing speed of the DVR 110 may considerably decrease or the DVR 110 may fail to properly operate. That is, the stability of the operation of the DVR 110 may considerably decrease.
Network traffic that is irrelevant to network monitoring may make it difficult to properly transmit data via a network. In a case in which the PC 140 is configured to be able to access the IP cameras 120 and the network storage 130 at any time, the IP cameras 120 or the network storage 130 may be subject to an attack by hackers.